Integrated artificial magnetic launch surface for near field communication system

ABSTRACT

A system is provided in which a set of modules each have a substrate on which is mounted a radio frequency (RF) transmitter and/or an RF receiver coupled to a near field communication (NFC) coupler located on the substrate. Each module has a housing that surrounds and encloses the substrate. The housing has a port region on a surface of the housing. Each module has a field confiner located between the NFC coupler and the port region on the housing configured to guide electromagnetic energy emanated from the NFC coupler through the port region to a port region of an adjacent module. An artificial magnetic conductor surface is positioned adjacent the backside of each NFC coupler to reflect back side electromagnetic energy with a phase shift of approximately zero degrees.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is related to U.S. patent application Ser. No.______ (attorney docket TI-78012) filed Jun. 29, 2017; U.S. patentapplication Ser. No. ______ (attorney docket TI-78013) filed Jun. 29,2017; and U.S. patent application Ser. No. ______ (attorney docketTI-78571) filed Jun. 29, 2017. These three applications are incorporatedby reference herein.

FIELD OF THE DISCLOSURE

This disclosure generally relates to the use of near field communication(NFC) in place of physical/ohmic contacts for communication among systemmodules.

BACKGROUND OF THE DISCLOSURE

Near Field Communication (NFC) is a wireless technology allowing twodevices to communicate over a short distance of approximately 10 cm orless. Various protocols using NFC have been standardized internationallywithin NFC Forum specifications and defined in ISO/IEC 18092, ECMA-340,and ISO 14443, for example. NFC allows a mobile device to interact witha subscriber's immediate environment. With close-range contactlesstechnology, mobile devices may be used as credit cards, to access publictransportation, to access secured locations, and many more applications.Contactless systems are commonly used as access control ID's (e.g.employee badges), as well as payment systems for public transportationetc. More recently, credit cards are beginning to include NFCcapability.

Typical NFC systems rely on low-frequency signals with structures suchas coils or capacitive plates with large fringing electric or magneticfields to facilitate signal transfer over a short distance. However,these low frequencies limit data rate. To increase data rate, thefrequency of the carrier must be increased, and a large bandwidth aroundthat carrier must be allocated.

Permittivity is a material property that expresses a measure of theenergy storage per unit meter of a material due to electric polarization(J/V²)/(m). Relative permittivity is the factor by which the electricfield between the charges is decreased or increased relative to vacuum.Permittivity is typically represented by the Greek letter E. Relativepermittivity is also commonly known as dielectric constant.

Permeability is the measure of the ability of a material to support theformation of a magnetic field within itself in response to an appliedmagnetic field. Magnetic permeability is typically represented by theGreek letter p.

A dielectric is an electrical insulator that can be polarized by anapplied electric field. When a dielectric is placed in an electricfield, electric charges do not flow through the material as they do in aconductor, but only slightly shift from their average equilibriumpositions causing dielectric polarization. Because of dielectricpolarization, positive charges are displaced toward the field andnegative charges shift in the opposite direction. This creates aninternal electric field which reduces the overall field within thedielectric itself. If a dielectric is composed of weakly bondedmolecules, those molecules not only become polarized, but also reorientso that their symmetry axis aligns to the field. While the term“insulator” implies low electrical conduction, “dielectric” is typicallyused to describe materials with a high polarizability, which isexpressed by a number called the relative permittivity (er). The terminsulator is generally used to indicate electrical obstruction while theterm dielectric is used to indicate the energy storing capacity of thematerial by means of polarization.

BRIEF DESCRIPTION OF THE DRAWINGS

Particular embodiments in accordance with the disclosure will now bedescribed, by way of example only, and with reference to theaccompanying drawings:

FIG. 1 is a block diagram of an exemplary system that uses guided NFCcommunication between modules;

FIGS. 2-4 are more detailed illustrations of modules for the system ofFIG. 1;

FIGS. 5A, 5B, 6A, 6B, 7A, 78B, and 8 are illustrations of exemplarymodal launching structures;

FIGS. 9 and 10 are views of an example artificial magnetic conductorsurface;

FIG. 11 is a plot illustrating performance of the slot antenna of FIG.6A combined with an artificial magnetic conductor surface;

FIG. 12 is a cross section of another embodiment of modules in which NFCcommunication is aided with skewed field confinement modules;

FIG. 13 is a pictorial illustration of the exemplary system of FIG. 10;and

FIG. 14 is a flow chart illustrating operation of NFC between adjacentmodules.

Other features of the present embodiments will be apparent from theaccompanying drawings and from the detailed description that follows.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE DISCLOSURE

Specific embodiments of the disclosure will now be described in detailwith reference to the accompanying figures. Like elements in the variousfigures are denoted by like reference numerals for consistency. In thefollowing detailed description of embodiments of the disclosure,numerous specific details are set forth in order to provide a morethorough understanding of the disclosure. However, it will be apparentto one of ordinary skill in the art that the disclosure may be practicedwithout these specific details. In other instances, well-known featureshave not been described in detail to avoid unnecessarily complicatingthe description.

As mentioned above, Near Field Communication (NFC) is a short-rangewireless connectivity technology that uses magnetic field induction toenable communication between devices when they are touched together, orbrought within a few centimeters of each other. Several communicationprotocols using NFC have now been standardized, such as ISO/IEC 18092,ECMA-340, and ISO 14443, for example. The various standards specify away for the devices to establish a peer-to-peer (P2P) network toexchange data.

Contactless systems are commonly used as access control ID's (e.g.employee badges), as well as payment systems for public transportationetc. More recently, credit cards are beginning to include NFCcapability. However, waves in open space propagate in all directions, asspherical waves. In this way, the far field loses power proportionallyto the square of the distance; that is, at a distance R from the source,the power is the source power divided by R squared. Such random wavepropagation may also result in interference to other systems that arelocated nearby and be in violation of emission limits set by standardbodies such as FCC.

Typical near field communication systems (NFC) rely on low-frequencysignals with structures like coils or capacitive plates with largefringing electric or magnetic fields to perform signal transfer over ashort distance (several mm). However, these low frequencies limit datarate. To increase data rate, the frequency of the carrier must beincreased, and a large bandwidth around that carrier must be allocated.Typical NFC techniques do not work well at high frequencies becauseinductive and capacitive communication works best when the distance andcoil/capacitor size is much shorter than the wavelength. For example,13.56 MHz has a wavelength of 22 meters, while 13.56 GHz has awavelength of only 22 millimeters.

Embodiments of the present disclosure may increase the frequency andbandwidth of NFC systems by using a dielectric or metallic/dielectricfield confinement block to confine the electromagnetic fields betweenthe transmitter (Tx) and receiver (Rx), and by using modal launchingstructures that launch suitable modes (TE10, TE11 for example) totransmit and receive the fields over a large bandwidth. An artificialmagnetic conductor (AMC) surface may be positioned behind the modallaunching structure to redirect a backside field to the desireddirection of propagation.

A dielectric field confiner may be used to confine the wave topropagation in one dimension, so that under ideal conditions the waveloses no power while propagating. A NFC field confiner (FC) may be usedas a medium to communicate between modules in a system, for example. TheFC may be a simple block of dielectric selected to have a highpermittivity or a high permeability in order for it to confine NFCenergy by reducing the wavelength of the radiated energy. The dielectricmay also be coated with a conductive or non-conductive material forbetter confinement.

A NFC field confiner may also be constructed from a metamaterial.Metamaterials are smart materials engineered to have properties thathave not yet been found in nature. They are made from assemblies ofmultiple elements fashioned from composite materials such as metals orplastics. The materials are usually arranged in repeating patterns, atscales that are smaller than the wavelengths of the phenomena theyinfluence. Metamaterials derive their properties not from the propertiesof the base materials, but from their newly designed structures.Metamaterials may be designed to have a negative relative permittivityand/or a negative relative permeability. Such matamaterials may bereferred to as “negative index materials.” Metamaterials are now wellknown and need not be described further herein; see, e.g.“Metamaterials,” Wikipedia, as of Dec. 2, 2015, which is incorporated byreference herein.

Using NFC coupling with an AMC surface reflector and a field confiner todistribute signals between various modules may provide a low costinterconnect solution. Embodiments of this disclosure provide a way tointerface removable system modules without using physical/ohmiccontacts.

FIG. 1 is a block diagram of an exemplary programmable logic controller100 that uses guided NFC communication between modules. A programmablelogic controller (PLC), or programmable controller, is a digitalcomputer used for automation of typically industrial electromechanicalprocesses, such as control of machinery on factory assembly lines,amusement rides, light fixtures, etc. PLCs are used in many machines, inmany industries. PLCs are designed for multiple arrangements of digitaland analog inputs and outputs, extended temperature ranges, immunity toelectrical noise, and resistance to vibration and impact. Programs tocontrol machine operation are typically stored in battery-backed-up ornon-volatile memory. A PLC is an example of a “hard” real-time systemsince output results must be produced in response to input conditionswithin a limited time; otherwise, unintended operation may result. PLCsystems are well known and need not be described in detail herein; e.g.see: “Programmable Logic Controller,” Wikipedia, as of Dec. 1, 2015,which is incorporated by reference herein.

In this example, there are several modules that will be referred to as“line cards.” Various types of line cards may be installed in a chassisor rack and configured for various purposes, such as: to controlmanufacturing processes, to control the heating and cooling in abuilding, to control medical equipment, etc. As such, electricalisolation is often needed or desirable to prevent ground loops or otherinteractions between various pieces of equipment that are beingcontrolled. In the past, various types of isolation devices have beenused, such as: optical isolators, transformers, etc.

In this example, there is a power supply line card 102, a datacommunication line card 110, and several processing line cards 120,120-2, 120-n. While five line card modules are illustrated in FIG. 1, atypical chassis may accommodate ten or more modules. While a systemusing line cards is illustrated herein, embodiments of the disclosureare not limited to line cards. Various types of modules may make use ofthe communication techniques explained herein in order to providereliable communication between removable modules.

In this example, supply line card 102 is coupled to a source of powerand in-turn may produce one or more voltages that may be distributed viaa bus 104 that may be coupled to each of the line cards via connectorssuch as connector 105. Typically, voltage bus(es) 104 may be included ina backplane that provides support for the connectors 105.

Data communication line card 110 may be configured to send and receivedata via a communication channel to a remote host or another rack orchassis, for example. Various types of communication line card 110 mayaccommodate a wireless or wired interface. For example, an internetconnection to a local or a wide area net may be provided by line card110. Alternatively, a wireless connection to a Wi-Fi network or to acellular network may be provided by line card 110.

Processing line card 120 may include, front end interface logic 130,processing logic 131, and aggregator logic 132, for example. Front endinterface logic 130 may be of various types to provide interconnectionto equipment that is being controlled, such as: input and outputsignals, RS232/422/485 compatible signals, digital signals, analogsignals, etc. Various types of logic may be provided, such as: analog todigital converters (ADC), digital to analog converters (DAC), relays,contacts, etc. Processing logic 131 may include various types ofhardwired and programmable logic, microcontrollers, microprocessors,memory, etc. Line cards 120-2, 120-n, etc may be identical or similar toline card 120 and may include various types and combinations ofprocessing and interface logic as needed for a given control task.

In this example, each line card is configured to allow it to communicatewith its nearest neighbor on both sides. For example, line card 110 maytransmit via transmitter 111 to line card 120 which has a receiver 124.Similarly, line card 120 may transmit via transmitter 123 to receiver115 on line card 110. At the same time, line card 120 may transmit viatransmitter 122 to adjacent line card 120-n and receive via receiver 121from adjacent line card 120-2.

In a similar manner, each line card in system 100 may communicate witheach other line card in a daisy chain manner. Each line card includes anaggregator/de-aggregator logic function, such as 132 on line card 120that allows each line card to recognize communication on the daisy chainintended for it. The aggregator/de-aggregator function also allows aline card to originate a communication packet that is then provided tothe daisy chain and then propagated through adjacent line cards to afinal destination on a target line card. In this embodiment, the daisychain operates in a similar manner to an internet network protocol andeach aggregator 132 functions as an internet interface. In anotherembodiment, a different type of known or later developed peer to peerprotocol may be used.

As mentioned above, NFC may be used as the transport vehicle tocommunicate between each adjacent line card. As will be described inmore detail below, FC segments, such as FC 115, 225 and 116, 126 may beused to guide the NFC between each adjacent line card module in order tominimize signal spreading and interface to other systems and devices.

FIGS. 2 and 3 are more detailed illustrations of modules for the systemof FIG. 1. FIG. 2 illustrates an example line card module 221 that isrepresentative of the various modules 110, 120, 120-2, 120-n, etc ofsystem 100. Module 221 may include a substrate 250 on which are mountedvarious circuit components, such as an integrated circuit (IC) 251 thatincludes transmitter(s) and receivers(s), such as transmitter 123 andreceiver 124 and/or transmitter 122 and receiver 121, of line card 120,for example. In some embodiments, there may be a separate IC for eachtransmitter and receiver. In another embodiment, one or more receiversand transmitters may be formed in a single IC, for example.

Integrated circuit 251 may also include aggregation logic, processinglogic and front end logic, or there may be additional ICs mounted onsubstrate 250 that contain aggregation logic, processing logic, andfront end logic. Substrate 250 may be a single or a multilayer printedcircuit board, for example. IC 251 and other ICs may be mounted onsubstrate 250 using through hole or surface mount technology usingsolder bumps or bonding depending on the frequency of operation, orother known or later developed packaging technologies. Substrate 250 maybe any commonly used or later developed material used for electronicsystems and packages, such as: fiberglass, plastic, silicon, ceramic,acrylic, etc., for example.

Substrate 250 may also include an NFC coupler 252 that is connected tothe receiver and/or transmitter that is contained within IC 251. NFCcoupler 252 will be described in more detail below. The coupler may be aseparate structure that is mounted on substrate 250, or it may beembedded within substrate 250. Embodiments of the disclosure may operatein near field mode in which the separation between adjacent modules is afraction of the wavelength of the frequency being transmitted by thetransmitter(s) in IC 251. For example, transmission frequencies in arange of 5 GHz to 100 GHz may be used. However, some embodiments may usefrequencies that are higher or lower than this range.

As will be described in more detail below, an artificial magneticconductor (AMC) surface 280 may be positioned behind the modal launchingstructure 252 to redirect a backside field to the desired direction ofpropagation.

Near field mode may produce an evanescent field that may be used tocouple two adjacent NFC couplers. Evanescent fields by nature exhibit anexponential decay with distance away from surface. By virtue of nearproximity between NFC coupler 252 and another NFC coupler in an adjacentmodule that is only a few mm's away, enhanced by FC 260, a reasonableTX-to-RX signal coupling may be achieved using the evanescent field innear field mode while mitigating emission limits/concerns outlined perFCC Part 15.

The best analogy would be that of a transformer. A strong self-couplingbetween coils results in reduced leakage to the external world.Furthermore, any leakage may be considered un-intentional. Therequirements for un-intentional radiation per FCC is greatly relaxedcompared to those for intentional emissions.

Module 221 may be enclosed in a housing that is roughly indicated at240. One side of the housing is illustrated as panel 241, which may bemetal or plastic, for example. Typically, the housing will be a few mmthick.

An NFC field confiner 260 may be mounted to panel 241 in a position thatplaces it approximately centered over and adjacent NFC coupler 252 whenhousing 240 is assembled, as indicated by motion vector 270. Whenhousing 240 is assembled, a top surface of NFC coupler 252 will bepositioned immediately adjacent a bottom surface of field confiner 260,as indicated by vector 270. In this manner, a majority of theelectromagnetic energy that is emanated by NFC coupler 252 will becaptured and confined by field confiner 260 and thereby directed to anadjacent module with minimal external radiation and signal loss.

Field confiner 260 may also increase the field strength of theevanescent field produced by NFC coupler 252. Field confiner 260 mayalso reduce radiation leakage and thereby contribute to FCC (FederalCommunication Commission) compliance. Operation in the 5-100 GHz regionproduces cm/mm-wave frequencies that allow for relaxed spatial alignmenttolerance between NFC coupler 252 and NFC field confiner 260.

Field confiner 260 may be a dielectric block, for example.Electromagnetic wave propagation through the dielectric block may bedescribed by the wave equation, which is derived from Maxwell'sequations, and where the wavelength depends upon the structure of thedielectric block, and the material within it (air, plastic, vacuum,etc.), as well as on the frequency of the wave. Field confiner 260 maybe able to confine the field emitted by NFC coupler 252 by having apermittivity and/or permeability that is significantly greater thansurrounding materials and/or air which will significantly reduce thewavelength of the electromagnetic field emitted by NFC coupler 252. Forexample, field confiner 260 may be a dielectric block that has arelative permittivity greater than approximately 2.0. Similarly, fieldconfiner 260 may be a dielectric block that has a relative permeabilitygreater than approximately 2.0.

Similarly, field confiner 260 may be able to confine the field emittedby NFC coupler by having a permittivity and/or permeability that issignificantly lower than surrounding materials and/or air which willsignificantly increase the wavelength of the electromagnetic fieldemitted by NFC coupler 252. For example, field confiner 260 may beconstructed from a negative index metamaterial that causes a significantreduction in wavelength of the electromagnetic field emitted by NFCcoupler 252.

In another embodiment, field confiner 260 may be able to confine thefield emitted by NFC coupler 252 by having a permittivity and/orpermeability that is only slightly greater than surrounding materialsand/or air which will reduce the wavelength of the electromagnetic fieldemitted by NFC coupler 252. For example, field confiner 260 may be adielectric block that has a relative permittivity greater thanapproximately 1.0 if the surrounding material is air. Similarly, fieldconfiner 260 may be a dielectric block that has a relative permeabilitygreater than approximately 1.0 if the surrounding material is air.

In another embodiment, field confiner 260 may have a conductive layeraround the periphery to further confine and direct an electromagneticfield radiated by NFC coupler 252. The conductive layer may use ametallic or non-metallic conductive material to form sidewalls aroundconfiner 260, such as: metals such as copper, silver, gold, etc., aconductive polymer formed by ionic doping, carbon and graphite basedcompounds, conductive oxides, etc., for example.

Depending on the material and thickness of module wall 241, fieldconfiner 260 may be simply mounted to the inside surface of module wall241 such that the radiated signal passes through module wall 241. Insome embodiments, a window may be provided in module wall 241 so that anouter surface of field confiner 260 may be mounted flush, slightlyindented, or slightly proud of an outside surface of module wall 241,for example. The general location on the surface of the housing wherethe field confiner is located will be referred to herein as a “port.”

In another embodiment, field confiner 260 may be mounted directly onsubstrate 250 such that it covers over NFC coupler 252 and is configuredto span between the substrate and side panel 241 when housing 240 isassembled.

FIG. 3 illustrates a portion of a second module 322 that may be locatedadjacent module 221. Module 322 may have a housing that includes a panel342, that will be referred to as a “left” panel. Module 221 may have apanel 241 that will be referred to as a “right” panel. Module 322 mayinclude a substrate 350 that holds various ICs, such as IC 351 that mayinclude a receiver and transmitter, an NFC coupler 352 that may besimilar to coupler 252, referring back to FIG. 2, and an AMC surface 380that will be described in more detail below. Module 322 may also includea field confiner 361 that is mounted on left panel 342 or on substrate350 and in alignment with the NFC coupler on substrate 350.

When module 221 and module 322 are installed in a chassis, right panel241 will be in close proximity to left panel 342, as indicated at 371.Field confiner 260 of module 221 and field confiner 355 of module 322are configured so that they are in approximate alignment with eachother. In this manner, a signal that is generated by a transmitter in IC251 may be provided to coupler 252, radiated into field confiner 260 andthereby directed to field confiner 361 and then received by coupler 352on substrate 350 and thereby provided to a receiver in IC 351.

Module 221 or 322 may be easily removed from or inserted into a chassiswithout any wear and tear on contacts that were previously required tocommunicate signals between modules. Furthermore, dielectric fieldconfiners 260, 361 provide complete electrical isolation between module221 and module 322. An additional isolation mechanism is not required.

FIG. 4 is a more detailed illustration of two modules 421, 422 that aresimilar to modules 221, 322 of FIG. 3. This view is representative of across sectional view of the modules looking towards the backplane. Inthis example, modules 421, 422 are packaged in plastic housings thateach may be formed as two “clam shells” as indicated at 441, 442. Whiletwo package elements are illustrated here, other embodiments may beassembled using various configurations of packaging that may have morethan two parts, for example.

Each module may have one, or more, substrates, such as substrate 450. Inthis example, substrate 450 is a multilayer printed wiring board (PWB);however, other embodiments may use two PWBs mounted back to back, forexample. One or more ICs 451 are mounted on substrate 450 and containthe transmitter and receiver, as described above in more detail.Processing logic and aggregator logic may also be included in the one ormore ICs 451. A “left” NFC 453 is formed on the left surface ofsubstrate 450 and a “right” NFC coupler 452 is formed on the rightsurface of substrate 450. Left NFC coupler 453 may be coupled to areceiver in IC 451 via a stripline 455 formed on one or more layers ofsubstrate 450. Similarly, right NFC coupler 452 may be coupled totransmitter in IC 451 via a stripline 454 formed on one or more layersof substrate 450. The striplines may be single ended or differential, aswill be described in more detail below.

A shield 480 may be provided between left NFC coupler 453 and right NFCcoupler 452 to minimize “back scatter” of the field produced by each NFCcoupler. Shield 480 may be an artificial magnetic conductor (AMC)structure, for example. AMC 480 may include several conductive layers,as will be described in more detail below. AMC structures are typicallyrealized based on periodic dielectric substrates and variousmetallization patterns. One of the conductive layers of AMC 480 may beconnected to a ground reference for the module.

Due to the magnet field zero phase shift characteristics of AMC 480within its useful bandwidth, little or no spacing 473 is requiredbetween AMC 480 and each coupler 452, 453 in order for a reflectedelectric field from AMC 480 to be combined with an electric fieldoriented in a desired direction toward the port region of module 421.Conversely, if a simple ground plane shield is used as an electric fieldreflector to produce a reflected electric field with a phase shift of90°, then the ground plane shield would need to be spaced apart fromeach coupler 452, 453 by a distance of approximately lambda/4, wherelambda is the wavelength of the signal being emitted by the couplers, inorder for the reflected field to combine correctly with the forwardfacing field. For example, the wavelength of a 30 GHz signal in adielectric having an ε_(R) of 1 is approximately 10.0 mm. In thisexample, substrate 450 is a typical PWB material that has an ε_(R) ofapproximately 1.0. Therefore, an electric field reflector needs to bespaced away from each coupler by a distance 473 of approximately 2.5 mm,in a system operating at 30 GHz. Lower frequency operation may requirelarger spacing. Thus, the use of AMC 480 to provide magnetic fieldreflection may allow the use of thinner substrates and modules that makeuse of NFC.

As discussed above, NFC field confiners 460, 461 may be positioned aboveeach NFC coupler 452, 453 and operate to confine a majority of the fieldradiated from each coupler. In this example, each NFC field confiner isa simple block of dielectric material, which will be referred to as a“field confiner” (FC) herein. Common dielectric materials have arelative permittivity (ε_(R)) of approximately 2-3, for example. Theexact size of the block is not critical.

When module 421 and module 422 are placed adjacent to each other, theNFC port of module 421 formed by NFC coupler 452 and FC 460 and the NFCport of module 422 formed by NFC coupler 453-2 and FC 461-1 will form anelectro-magnetic (EM) coupling that allows a signal generated by atransmitter in IC 451 to be EM coupled from NFC coupler 452 to NFCcoupler 453-2 via FC 460 and 461-1 and then provided to a receiver in IC451-1. A similar process may be used to transmit a signal from atransmitter in IC 451-1 to a receiver in IC 451 by using a second set ofNFC couplers or by sharing NFC couplers 452, 453-2 s.

In this example, the FC protrude through an opening in the housing walland the outside surface edge of FC 460 and 461-1 are flush with theoutside surface of the housing, such that the gap 471 between housingsof module 421 and 422 determines the gap between FC 460 and 461-1.Minimizing the gap will minimize the amount of radiated energy theescapes while crossing the gap.

In another embodiment of a module 421, NFC field confiners 460, 461 maybe configured to stop at the inside surface of module housing panels441, 442. In this case, the dielectric characteristics of housing panels441, 442 may be chosen to be approximately equal to the dielectriccharacteristics of NFC field confiners 460, 461, for example.

Alternatively, the outside surface of the NFC field confiners may standproud of the outside surface of the housing panel. In this manner, thegap between adjacent NFC field confiners may be reduced.

In another embodiment, a flexible, non-conducting layer may be added toone or both surfaces of adjoining NFC field confiners of modules inorder to fill the gap between modules. An example of a rubbery materialwith dielectric constant 2.5 to 3.5 is Silicone. Other materials withsimilar characteristics that may be used fall into two types:unsaturated rubber and saturated rubber.

Unsaturated rubbers include: Synthetic polyisoprene, Polybutadiene,Chloroprene rubber, Butyl rubber, Halogenated butyl rubbers,Styrene-butadiene Rubber, Nitrile rubber, Hydrogenated Nitrile Rubbers,etc, for example.

Saturated rubbers include: EPM (ethylene propylene rubber), EPDM rubber(ethylene propylene diene rubber), Epichlorohydrin rubber (ECO),Polyacrylic rubber (ACM, ABR), Silicone rubber (SI, Q, VMQ),Fluorosilicone Rubber (FVMQ), Fluoroelastomers (FKM, and FEPM) fluororubber, fluorocarbon rubber, Perfluoroelastomers (FFKM), Polyether blockamides (PEBA), Chlorosulfonated polyethylene synthetic rubber (CSM),Ethylene-vinyl acetate (EVA), etc, for example.

FIGS. 5A, 5B, 6A, 6B, 7A, 7B, and 8 are illustrations of exemplary modallaunching structures. FIG. 5A is a bottom view and FIG. 58B is an edgeview of substrate 501. Substrate 501 is representative of a portion of asubstrate in one module on which an NFC field coupler is formed, such assubstrate 450 in module 421 of FIG. 4, for example. NFC field confiner560 is positioned adjacent substrate 501 and roughly aligned with theNFC field coupler formed thereon.

In this example, at least a portion of the bottom side of substrate 501is covered by a conductive layer, such as a copper layer. The NFC fieldcoupler is formed by etching a circular slot 505, leaving the conductiveouter portion 507 and a conductive inner portion 506. On the top side ofsubstrate 501, stripline line 503 is arranged to bring a signalgenerated by a transmitter within IC 530 that is mounted on thesubstrate, as described in more detail above. Stripline line 503 passesover slot 505 and terminates over conductive inner portion 506. Thisarrangement will excite a traveling wave mode that goes around in acircle on the slot 505 in response to an RF signal on stripline line503. This configuration will excite a wide band field structure with alarge near field that will extend in a perpendicular direction from theslot structure. In another embodiment, the top and bottom layers ofsubstrate 501 may be reversed.

In another embodiment, there may be two stripline lines in place ofstripline line 503 that are arranged to provide a differentialexcitation signal to circular slot 505, as described in more detail inU.S. Pat. No. 9,590,699, entitled “Guided Near Field Communication forShort Range Data Communications,” Swaminathan Sankaran et al, grantedMar. 7, 2017, and which is incorporated by reference herein.

AMC structure 580 may be placed on the “back side” of substrate 501 thatis opposite to FC 560. In this example, AMC structure 580 is formed as aseparate component that is then mounted on substrate 501 using a set ofsolder bumps such as illustrated at 584. AMC structure 580 may includetwo conductive layers 581, 582 separated by a dielectric layer 583.Layer 581 may cover the entire backside of AMC structure 580 and becoupled to ground reference layer 507 through via(s) 585 throughdielectric 583, solder bumps 584, and via(s) 586 in substrate 501.

In another embodiment, AMC structure 580 may be formed using conductivelayers that are part of substrate 501. For example, referring back toFIG. 4, AMC structure 480 is fashioned from three conductive layerswithin substrate 450. A central conductive layer and two outer patternedlayers embody two AMC surfaces that are back-to-back and providemagnetic reflection for modal antenna 452 and also for modal antenna453.

Referring to FIG. 4, a mirror image structure may be formed in asubstrate for another module, such as substrate 450-1 of module 422 asshown in FIG. 4, and will couple with the large near field produced byslot 505. Field confiners 460, 461-1 act to confine the field within thelimits of field confiners 460, 461-1. In this manner, a signal generatedby a transmitter in IC 451 mounted on substrate 450 may be EM coupled toa coupling structure on substrate 450-1 and passed to a receiver in IC451-1 mounted on substrate 450-1 without physical ohmic connectors andwith minimal escaped radiation.

FIG. 6A is a bottom view and FIG. 6B is an edge view of substrate 601.Substrate 601 is representative of a portion of a substrate in onemodule on which an NFC field coupler is formed, such as substrate 450 inmodule 421 of FIG. 4, for example. NFC field confiner 560 is positionedadjacent substrate 601 and roughly aligned with the NFC field couplerformed thereon.

In this example, at least a portion of the bottom side of substrate 601is covered by a conductive layer, such as a copper layer. The NFC fieldcoupler is formed by etching a straight slot 605, leaving the conductiveouter portion 607. On the top side of substrate 601, stripline line 603is arranged to bring a signal generated by a transmitter within IC 530that is mounted on the substrate, as described in more detail above.Stripline line 603 passes over slot 605 and terminates over conductiveouter portion 606. This arrangement will excite a hybrid TE mode on theslot 605 in response to an RF signal on stripline line 603. Thisconfiguration will excite a wide band field structure with a large nearfield that will extend in a perpendicular direction from the slotstructure. In another embodiment, the top and bottom layers of substrate601 may be reversed.

AMC structure 580 may be placed on the “back side” of substrate 601 thatis opposite to FC 610. In this example, AMC structure 580 is formed as aseparate component that is then mounted on substrate 601 using a set ofsolder bumps such as illustrated at 584. AMC structure 620 may includetwo conductive layers separated by a dielectric layer, as described inmore detail above.

FIG. 7A is a top view and FIG. 7B is an edge view of substrate 701.Substrate 701 is representative of a portion of a substrate in onemodule on which an NFC field coupler is formed, such as substrate 450 inmodule 421 of FIG. 4, for example. NFC field confiner 760 is positionedadjacent substrate 701 and roughly aligned with the NFC field couplerformed thereon.

In this example, at least a portion of the bottom side of substrate 701is covered by a conductive layer, such as a copper layer 707. On the topside of substrate 701, a fractal pattern 705 is patterned from aconductive layer. A stripline line 703 is arranged to bring a signalgenerated by a transmitter within IC 530 that is mounted on thesubstrate, as described in more detail above. Stripline line 703 iscoupled to conductive fractal pattern 705. This arrangement will excitea traveling wave in response to an RF signal on stripline line 703. Thisconfiguration will excite a wide band field structure with a large nearfield that will extend in a perpendicular direction from the fractalstructure.

In this example, an AMC structure is not needed since solid conductivelayer 707 provides electric field reflection of the field formed byfractal patter 705. However, as described above, the distance betweenreflective layer 707 and fractal pattern 705 should be approximatelylambda/4 of the operating frequency for best results.

FIG. 8 is an edge view of substrate 801. Substrate 801 is representativeof a portion of a substrate in one module on which an NFC field coupleris formed, such as substrate 450 in module 421 of FIG. 4, for example.NFC field confiner 860 is positioned adjacent substrate 801 and roughlyaligned with the NFC field coupler formed thereon.

In this example, at least a portion of the bottom side of substrate 801is covered by a conductive layer, such as a copper layer 807. On the topside of substrate 801, another conductive layer may be pattered tocontact a conductive outer surface of FC 860. A stripline line 803 isarranged to bring a signal generated by a transmitter that is mounted onthe substrate to a straight wire antenna 804 that may be positionedwithin a lower region of FC 860.

In this example, an AMC structure is not needed since solid conductivelayer 807 provides electric field reflection of the field formed by wireantenna 804. However, as described above, the distance betweenreflective layer 807 and wire antenna 804 should be approximatelylambda/4 of the operating frequency for best results. Elevating wireantenna 804 into a lower region of FC 860 allows the thickness ofsubstrate 801 to be minimal while still providing the requiredseparation between wire antenna 804 and electric field reflector 807.

In another embodiment, an AMC may be positioned below wire antenna 804in place of ground plane 807. In this case, the separation of wireantenna 804 and the AMC is not critical since the electromagneticreflections from the AMC are in-phase with the main portion of theelectromagnetic wave emanated from wire antenna 804.

This arrangement will excite a TE mode in response to an RF signal onstripline line 803. This configuration will excite a wide band fieldstructure with a large near field that will extend in a perpendiculardirection from the wire antenna structure.

FIGS. 9 and 10 are views of an example artificial magnetic conductorsurface. An AMC, also known as a high-impedance surface, is a type ofelectromagnetic band gap (EBG) material or artificially engineeredmaterial with a magnetic conductor surface for a specified frequencyband. Various types of AMC surfaces have been used as a ground plane fora low profile antenna, such as: a mushroom-like EBG, uniplanar compactEBG (UCEBG), Peano curve, and Hilbert curve. See, for example, J. R.Sohn, K. Y. Kim, and H.-S. Tae, COMPARATIVE STUDY ON VARIOUS ARTIFICIALMAGNETIC CONDUCTORS FOR LOW-PROFILE ANTENNA, 2006.

AMC surfaces have very high surface impedance within a specific limitedfrequency range, where the tangential magnetic field is small, even witha large electric field along the surface. Therefore, an AMC surface canhave a reflection coefficient of +1, which is in-phase reflection.Generally, the reflection phase is defined as the phase of the reflectedelectric field which is normalized to the phase of the incident electricfield at the reflecting surface. It can be called in-phase reflection,if the reflection phase is 00. In practice, the reflection phase of anAMC surface varies continuously from +1800 to −1800 relative to thefrequency, and crosses zero at just one frequency (for one resonantmode). However, a useful bandwidth may be obtained using known designtechniques. Thus, due to this unusual boundary condition, in contrast tothe case of a conventional metal plane, an AMC surface can function as areflective surface for low-profile modal antennas in an NFC system. Forexample, even though a horizontal modal antenna is extremely close to anAMC surface, the current on the antenna and its image current on theground plane are in-phase, rather than out-of phase, therebystrengthening the radiation.

FIG. 9 is an edge view of substrate 901 which is attached to a secondsubstrate 902. Substrate 901 is representative of a portion of asubstrate in one module on which an NFC field coupler is formed, such assubstrate 450 in module 421 of FIG. 4, for example. NFC field confiner960 is positioned adjacent substrate 901 and roughly aligned with NFCfield coupler 904 formed thereon. FC 960 may have conductive sidewalls961 that may be coupled to reference layer 905.

NFC coupler 904 may be implemented similarly to the examples of FIG. 5A,6A, or 8, for example. Transmitter and/or receiver circuitry may bemounted on substrate 901 and coupled to NFC coupler 904 as described inmore detail above. Conductive layer 907 may be patterned as describedabove to form NFC coupler 904. Layer 907 may be coupled to a groundreference.

AMC structure 980 may be placed on the “back side” of substrate 901 thatis opposite from FC 960. In this example, AMC structure 980 is formed asa separate component that is then mounted on substrate 901 using a setof solder bumps such as illustrated at 984. AMC structure 980 mayinclude two conductive layers 981, 982 separated by a dielectric layer983. Layer 981 may cover the entire backside of AMC structure 980 and becoupled to ground reference layer 907 through via(s) 985 throughdielectric 983, and solder bumps 984.

In another embodiment, AMC structure 980 may be formed using conductivelayers that are part of substrate 901. Since AMC structure 980 reflectselectromagnetic fields produced by NFC coupler 904 with no phase shift,AMC structure 980 does not need to be spaced away from NFC coupler 904.

FIG. 10 is a top view of substrate 902. In this example AMC, a latticeof square conductive patches 982 is patterned over dielectric layer 983.The size of the patches 982, the spacing between them, the thickness 987of dielectric layer 983 and the permittivity/permeability of dielectriclayer 983 are selected using known or later developed design parametersto form a structure that has an in-phase reflection property for anelectromagnetic wave at a frequency band of interest for NFC. In someembodiments, each patch 982 may have a via connecting it to ground plane981 (see FIG. 9). In other embodiments, there may be a narrow connectingstrap positioned between each adjacent patch 982. As mentioned above,various types of AMC surfaces have been used as a ground plane for a lowprofile antenna, such as: a mushroom-like EBG, uniplanar compact EBG(UCEBG) Peano curve, and Hilbert curve.

FIG. 11 is a plot illustrating a plot of S-parameters for of the slotantenna and field confiner of FIG. 6A combined with an artificialmagnetic conductor surface 580. S₂₁ plot line 1101 represents theforward voltage gain across a range of frequencies from 12 GHz to 19GHz, while S₁₁ plot line 1102 represents the input port voltagereflection coefficient across that range of frequencies. As shown by S₂₁plot line 1101, there is approximately no loss through the slot antennaand field confiner of FIG. 6A for the 3 GHz band of frequencies 1103centered about 16 GHz. S₁₁ plot line 1102 illustrates there is also alow reflection coefficient across the 3 GHz band 1103.

FIG. 12 is a cross section of another embodiment of modules in which NFCcommunication is aided with skewed field confinement blocks, such as FCblocks 1210, 2012 in module 1201 and in module 1202. Substrate 1221 inmodule 1201 may be a multilayer printed circuit board (PCB) thatincludes several conductive layers separated by dielectric layers. Thedesign and fabrication of PCBs is well known and need not be describedin detail herein. In this example, PCB 1221 may have an outer conductivelayer 1222 on one side, referred to herein as the “left side” andanother conductive layer 1224 on the opposite side, referred to hereinas the “right side.” Another conductive layer 1223 in the middle of PCB1221 may be patterned to form AMC patterns 1280, 1281 as described withregard to FIGS. 9-10. AMC pattern 1280 may interact with conductivelayer 1222 to form an AMC surface. Similarly, AMC pattern 1281 mayinteract with conductive layer 1224 to form another AMC surface.

NFC coupler 1231 may be formed on or near the left side surfaceproximate to AMC 1280. NFC coupler 1231 may be a modal launchingstructure as described with regards to FIG. 5A, 6A, 7A, 8, etc., forexample. Similarly, NFC coupler 1233 may be formed on or near the rightside surface proximate to AMC 1281. NFC coupler 1233 may be a modallaunching structure as described with regards to FIG. 5A, 6A, 7A, 8,etc., for example.

Module 1202 may include a PCB 1222 that has a similar configuration asPCB 1221. As described with regard to FIG. 1, modules 1221 and 1222 mayinclude various integrated circuits and other components in order toembody various line cards, processor cards, input/output cards, etc.

NFC coupler 1231 may be offset from NFC coupler 1233 so that AMC pattern1280 and 1281 may be fabricated in the same conductive layer 1223.However, if FC 1210 and 1212 are rectangular blocks, then port region1211 and 1213 in adjacent modules would not align with each other. Inthis example, field confiners 1210 and 1212 are skewed on order for portregions 1211 and 1213 to align with adjacent modules.

In this example, each module 1201, 1202 is approximately 10 mm wideinside the plastic housing. The wall thickness of the plastic housing isapproximately 1 mm and the modules are spaced apart by about 250 um wheninstalled in a chassis. Multilayer PCB 1221, 1222 is approximately 1 mmthick. NFC coupler 1231 and 1233 are offset from each other byapproximately 9 mm. Therefore, by skewing FC blocks 1210, 1212 at abouta forty-five degree angle, port regions 1211 and 1213 can be locatedapproximately opposite each other so that the port regions in adjacentmodules will align with each other. In another embodiment, the angle ofskew of the FC may be selected based on the width of the module,thickness of the PCB and spacing between the NFC couplers.

The outside surface 1215 of FC block 1210 and outside surface 1216 of FCblock 1212 may have a conductive material layer around the periphery tofurther confine and direct an electromagnetic field radiated by theassociated NFC coupler. This conductive layer may be coupled to avoltage reference signal, such as ground, that is included in the outerconductive layer 1222, 1224 of the PCB.

In another embodiment, a simple electric mode reflective layer may beused in place of AMC surfaces 1280, 1281. For example, conductive regionin layer 1222 may act as a reflector for NFC coupler 1233, whileconductive region in layer 1224 may act a reflector for NFC coupler1231. In this case, since the electric mode reflection produces a 90degree phase shift, the reflective layer should be spaced away from theNFC coupler by a distance of approximately one fourth of the wave lengthof the RF signal being transmitted.

FIG. 13 is a pictorial illustration of an exemplary system 1300 that isanother view of system 100 of FIG. 1. Backplane 1306 provides a set ofconnectors 1305 for providing power to each line card, as explained withregard to connector 105 of FIG. 1. As can be seen by the illustration,each line card module is removable from backplane 1306 by simply pullingthe module to disconnect it from connector 1305. Typically, a rack orchassis will also be provided along with backplane 1306 to support theline cards when they are inserted into connectors 1305.

Each line card module is enclosed in a housing, which may be made fromplastic or other suitable materials. As described in more detail above,each line card may have a NFC coupler, AMC surface, and field confinerarranged to form a contactless communication port on each side of themodule. For example, module 1310 may have a port 1355 on the right sideof the module while module 1320 may have a port 1356 on the left side ofthe module that aligns with port 1355 when both modules are plugged intobackplane 1306.

Similarly, module 1320 may have another port (not shown) on the rightside of the module while module 1340 may have a port (not shown) on theleft side of the module that aligns when both modules are plugged intobackplane 1306. All of the modules may have similar pairs of ports onboth sides of each module to allow daisy chained communication among allof the modules, as described in more detail above.

FIG. 14 is a flow chart illustrating operation of near fieldcommunication between modules, as described above in more detail. Asdescribed above in more detail, the modules may be part of aprogrammable logic control system used for industrial, commercial, andresidential applications. A typical system may include a rack or chassisinto which a set of modules are installed. Each module may communicatewith an adjacent neighbor module using near field communication, inwhich an RF signal generated in one module may be EM coupled to areceiver in an adjacent module using radiative coupling, near fieldcoupling, or evanescent coupling, or any combination of these modes.

For example, a radio frequency (RF) signal may be generated in a firstmodule as shown in block 1402. In the example of FIGS. 1-13, the RFsignal may have a frequency in the range of 10-30 GHz. However, othersystems may use RF signals at a higher or lower frequency by adjustingthe physical size of the field coupling and field confining componentsdescribed herein.

An RF electromagnetic field may be emanated in response to the RF signalfrom a first near field communication (NFC) coupler in the first moduleas shown in block 1404. The RF electromagnetic field may be the resultof a traveling wave formed in a circular slot in a conductive layer, forexample, as described in more detail with regard to FIGS. 5A-5B.Alternatively, the electromagnetic field may be the result of atraveling wave formed in a straight slot in a conductive layer, forexample, as described in more detail with regard to FIGS. 6A-6B. Inanother embodiment, the electromagnetic field may be the result of atraveling wave formed by a fractal pattern, for example, as described inmore detail with regard to FIGS. 7A-7B. In another embodiment, theelectromagnetic field may be the result of a traveling wave formed by astraight wire, for example, as described in more detail with regard toFIG. 8.

As described above in more detail, a portion of the emanated RF fieldmay occur on the backside of the NFC coupler. An artificial magneticconductor surface positioned adjacent the NFC coupler may reflect thebackside RF field as shown at 1406 with a zero phase shift so that it isadded to the front side RF field.

The emanated RF electromagnetic field is confined and directed by afield confiner in the first module to a field confiner in a secondmodule located adjacent the first module as shown in block 1408. Asdescribed in more detail above, the two field confiners are located inclose proximity when the modules are installed in a system and therebyminimize loss of emanated energy to the surroundings. This may simplifythe process of complying with FCC emission requirements, for example.

The emanated RF electromagnetic field is then coupled to a second NFCcoupler in the second module is shown in block 1410. As described abovein more detail, this coupling is performed by EM coupling and may usethe near field of the emanated electromagnetic field. This coupling mayalso make use of radiated energy that is propagated from the NFC couplerto the second NFC coupler. The coupling may also make use of anevanescent field that is formed by the first NFC coupler. Depending onthe spacing between the adjacent modules, one or a combination of thesecoupling modes may occur.

A resultant RF signal may then be provided to an RF receiver on thesecond module as shown in block 1412. As described above in more detail,the multiple modules in the system may communicate in a daisy chainedmanner such that any module may be able to communicate with any othermodule in the system.

A known standard communication protocol, such as the Internet Protocol(IP) may be used, treating the daisy chained NFC physical media as anEthemet. The Internet Protocol (IP) is the principal communicationsprotocol in the Internet protocol suite for relaying datagrams acrossnetwork boundaries. IP has the task of delivering packets from thesource host to the destination host solely based on the IP addresses inthe packet headers. For this purpose, IP defines packet structures thatencapsulate the data to be delivered. It also defines addressing methodsthat are used to label the datagram with source and destinationinformation. The first major version of IP, Internet Protocol Version 4(IPv4), is the dominant protocol of the Internet. Its successor isInternet Protocol Version 6 (IPv6).

Another embodiment may use another known or later developedcommunication protocol for communication using the daisy chained NFCphysical media as described herein.

In this manner, embodiments of the present disclosure may provide highthroughput communication between removable modules of a system usingnear field communication techniques. The techniques described herein maybe less expensive than alternatives such as optical couplers, forexample. NFC allows contactless communication between modules andthereby eliminates the need for additional isolation in systems that mayrequire isolation between modules.

OTHER EMBODIMENTS

While the disclosure has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various other embodiments of the disclosure will beapparent to persons skilled in the art upon reference to thisdescription. For example, while a programmable logic controller systemwas described, other types of modular systems may embody aspects of thepresent disclosure in order to improve reliability, ease ofconfiguration, electrical isolation, etc.

While an artificial magnetic conductor surface formed by an array ofsquare patches was illustrated herein, other forms of known or laterdeveloped AMC surfaces may be used in other embodiments. Various typesof AMC surfaces include, but are not limited to: mushroom-like EBG,uniplanar compact EBG, Peano curve, Hilbert curve, etc.

While modules in which the guided NFC ports are located on the side ofthe module were described herein, in another embodiment a port may belocated on an edge of a module with a mating port located on a backplaneor other surface that is adjacent to the edge of the module, forexample.

While a daisy-chained communication configuration was described herein,in another embodiment other topologies may be formed. For example, atree topology may be formed by providing a port on the backplane thatmates with an edge mounted port in each module.

While a simple dielectric block has been described herein, anotherembodiment may use a metallic or non-metallic conductive material toform sidewalls on the field confiner, such as: a conductive polymerformed by ionic doping, carbon and graphite based compounds, conductiveoxides, etc., for example.

A dielectric or metamaterial field confiner may be fabricated onto asurface of a substrate or module panel using an inkjet printing processor other 3D printing process, for example.

While field confiners with polymer dielectric cores have been describedherein, other embodiments may use other materials for the dielectriccore, such as ceramics, glass, etc., for example.

While dielectric cores with a square cross section are described herein,other embodiments may be easily implemented. For example, the dielectriccore may have a cross section that is rectangular, trapezoidal,cylindrical, oval, or other selected geometries.

While sub-terahertz signals in the range of 5-100 GHz were discussedherein, NFC couplers and FCs and systems for distributing higher orlower frequency signals may be implemented using the principlesdescribed herein by adjusting the physical size of the field confinercore accordingly.

Certain terms are used throughout the description and the claims torefer to particular system components. As one skilled in the art willappreciate, components in digital systems may be referred to bydifferent names and/or may be combined in ways not shown herein withoutdeparting from the described functionality. This document does notintend to distinguish between components that differ in name but notfunction. In the following discussion and in the claims, the terms“including” and “comprising” are used in an open-ended fashion, and thusshould be interpreted to mean “including, but not limited to . . . .”Also, the term “couple” and derivatives thereof are intended to mean anindirect, direct, optical, and/or wireless electrical connection. Thus,if a first device couples to a second device, that connection may bethrough a direct electrical connection, through an indirect electricalconnection via other devices and connections, through an opticalelectrical connection, and/or through a wireless electrical connection.

Although method steps may be presented and described herein in asequential fashion, one or more of the steps shown and described may beomitted, repeated, performed concurrently, and/or performed in adifferent order than the order shown in the figures and/or describedherein. Accordingly, embodiments of the disclosure should not beconsidered limited to the specific ordering of steps shown in thefigures and/or described herein.

It is therefore contemplated that the appended claims will cover anysuch modifications of the embodiments as fall within the true scope andspirit of the disclosure.

1. (canceled)
 2. A module comprising: a substrate on which is mounted aradio frequency (RF) transmitter coupled to a near field communication(NFC) coupler located on the substrate, wherein the NFC coupler has afront side and an opposite back side, and the RF transmitter isconfigured to generate an RF signal having a frequency; an artificialmagnetic conductor (AMC) surface, positioned proximate the back side ofthe NFC coupler and separated from the NFC coupler by less than onefourth of a wavelength of the RF signal, to reflect near-fieldelectromagnetic energy having the frequency of the RF signal withessentially zero phase shift; and a field confiner, located proximatethe front side of the NFC coupler, to propagate and/or evanescentlycouple near-field electromagnetic energy emanated from the NFC coupler.3. The module of claim 2, the AMC surface includes a first conductivelayer and a second conductive layer separated by a dielectric layer, thefirst conductive layer is patterned into an array of isolated conductiveregion and the second conductive layer is coupled to a ground referencefor the RF transmitter.
 4. The module of claim 3, wherein the substrateis a first substrate, and the AMC surface is formed in a secondsubstrate that is separate from the first substrate.
 5. The module ofclaim 2, further comprising: a housing that surrounds and encloses thesubstrate and the AMC surface, the housing having a port region on asurface of the housing; wherein the field confiner is located proximatethe front side of the NFC coupler between the NFC coupler and the portregion of the housing, the field confiner being operable to propagateand/or evanescently couple near-field electromagnetic energy emanatedfrom the NFC coupler through the port region.
 6. A module comprising: asubstrate on which is mounted a radio frequency (RF) transmitter coupledto a first near field communication (NFC) coupler located on thesubstrate, wherein the first NFC coupler has a front side and anopposite back side; a first artificial magnetic conductor (AMC) surfacepositioned proximate the back side of the first NFC coupler; a firstfield confiner, located proximate the front side of the first NFCcoupler, to propagate and/or evanescently couple near-fieldelectromagnetic energy emanated from the first NFC coupler; an RFcommunication circuit mounted on the substrate and coupled to a secondNFC coupler located on the substrate, wherein the second NFC coupler hasa front side and an opposite back side; a second AMC surface positionedproximate the back side of the second NFC coupler; and a second fieldconfiner located proximate the front side of the second NFC coupler, topropagate and/or evanescently couple near-field electromagnetic energyto the RF communication circuit.
 7. The module of claim 6, wherein thesecond AMC surface includes a first conductive layer and a secondconductive layer separated by a dielectric layer, the first conductivelayer is patterned into an array of isolated conductive region and thesecond conductive layer is coupled to a ground reference for the RFreceiver.
 8. The module of claim 7, wherein the second conductive layerof the first AMC surface and the second conductive layer of the secondAMC surface are the same layer.
 9. The module of claim 6, furthercomprising: a housing that surrounds and encloses the substrate and thefirst AMC surface and the second AMC surface, the housing having a firstport region on a first surface of the housing and a second port regionon a second surface of the housing; wherein the first field confiner islocated proximate the front side of the first NFC coupler between thefirst NFC coupler and the first port region of the housing, the firstfield confiner being operable to propagate and/or evanescently couplenear-field electromagnetic energy emanated from the first NFC couplerthrough the first port region; and wherein the second field confiner islocated proximate the front side of the second NFC coupler between thesecond NFC coupler and the second port region of the housing, the secondfield confiner being operable to propagate and/or evanescently couplenear-field electromagnetic energy from the second port region to thesecond NFC coupler.
 10. The module of claim 6, further comprising: abackplane with a plurality of locations for attaching a plurality ofmodules; and a plurality of modules attached to the backplane, whereineach of the modules has a first port region and a second port region;wherein the first port region of each module aligns with the second portregion of an adjacent module.
 11. The module of claim 5, wherein thefield confiner fills a gap between the port region of the surface of thehousing and the NFC coupler.
 12. The module of claim 11, wherein theport region is offset laterally from the NFC coupler, and the fieldconfiner is skewed to fill the gap between the port region of thesurface of the housing and the NFC coupler.
 13. The module of claim 2,wherein the field confiner is a dielectric block having a relativepermittivity greater than approximately 1.0.
 14. The module of claim 2,wherein the field confiner is a negative index metamaterial.
 15. Amodule comprising: a substrate on which is mounted a radio frequency(RF) transmitter coupled to a first near field communication (NFC)coupler located on the substrate, wherein the first NFC coupler has afront side and an opposite back side; an artificial magnetic conductor(AMC) surface positioned proximate the back side of the first NFCcoupler; a field confiner, located proximate the front side of the firstNFC coupler, to propagate and/or evanescently couple near-fieldelectromagnetic energy emanated from the first NFC coupler; and a secondNFC coupler located proximate the AMC surface, wherein the first andsecond NFC couplers are coupled to a plurality of transmitters and/orreceivers mounted on the substrate.
 16. The module of claim 2, whereinan electromagnetic field emanated from the NFC coupler has a frequencyin the range of approximately 5-100 GHz.
 17. The module of claim 2,wherein the field confiner has a conductive sidewall.
 18. (canceled) 19.The method of claim 20, wherein the module is a first module, and themethod further comprises: receiving the emanated first RFelectromagnetic field and the reflected portion of the emanated first RFelectromagnetic field by a third field confiner in a second modulelocated adjacent the first module; coupling the emanated first RFelectromagnetic field and the reflected portion of the emanated first RFelectromagnetic field to a third NFC coupler in the second module; andproviding a resultant RF signal to an RF receiver on the second module.20. A method of transmitting a signal in a system, the methodcomprising: generating a first radio frequency (RF) signal in a module;emanating a first RF electromagnetic field in response to the first RFsignal from a first near field communication (NFC) coupler in themodule; reflecting a portion of the emanated first RF electromagneticfield using a first artificial magnetic conductor (AMC) surface locatedproximate the first NFC coupler, such that the reflected portion is notphase shifted; confining and directing the emanated first RFelectromagnetic field and the reflected portion of the emanated first RFelectromagnetic field by a first field confiner to a first port regionin the module; generating a second radio frequency (RF) signal in themodule; emanating a second RF electromagnetic field in response to thesecond RF signal from a second NFC coupler in the module; reflecting aportion of the emanated second RF electromagnetic field using a secondAMC surface located proximate the second NFC coupler, such that thereflected portion is not phase shifted; and confining and directing theemanated second RF electromagnetic field and the reflected portion ofthe emanated second RF electromagnetic field by a second field confinerto a second port region in the module.